In sheet separating and feeding apparatus of, for example, the type shown in U.S. Pat. No. 2,635,874, issued Apr. 21, 1953 to LaBore et al and assigned to the assignee of the present invention, there is provided structure for manually incrementally adjusting the sheet feeding gap between the bottoms of a plurality of sheet separating stones and a feed deck, to accommodate the change in thickness, from stack to stack, of the sheets in respective stacks of sheets of substantially uniform thickness. As shown in FIG. 2 of LaBore et al Patent, the structure for adjusting the sheet feeding gap generally includes a four bar linkage system having a link which is adapted for carrying the sheet separating stones, a compression spring having one end seated against the housing and the other end connected for downwardly urging the stones carrying link, and a manually rotatable shaft which is threadably attached to the stone carrying link for moving the same, and thus the sheet separating stones, upwardly against the compression of the spring in order to widen the gap, and downwardly toward the deck to narrow the gap. Although the sheets which are slightly thicker than the opening afforded by the adjusted width of the sheet feeding gap are automatically accommodated, due to such sheets tending to upwardly displace the sheet separating stones against the compression of the spring, the operator is required to intervene to assist such upward displacement in the event that an unusually thick sheet is inadvertently or in certain instances purposely included in a given stack of sheets. In this connection, it is noted that it is the usual practice in Great Britain, due to the British postal rate break structure being different than it is in the United States, to consistently feed mailpieces of more widely varying thickness than is the usual practice in the United States. Thus, as shown in FIG. 2 of the LaBore et al Patent, the aforesaid gap adjusting structure additionally includes a knob attached to the stone adjusting shaft to facilitate manually lifting the stones, against the compression of the spring, for temporarily widening the gap sufficiently to accommodate the passage of thicker sheets which cannot fit beneath the separating stones, or sheets which fail to displace the stones for feeding purposes.
Experience has shown that machine operators often find it difficult to exert sufficient pulling force on the shaft lifting knob to raise the separating stones against the compression of the spring, as a result of which excessively long delays may be experienced in the course of feeding some stacks of sheets. To facilitate more rapidly raising the sheet separating stones, lifting handles have been provided to afford some mechanical advantages; for example as shown in pending U.S. Patent Application Ser. No. 937,807, filed Aug. 29, 1978 by J. A. Conti and N. A. Pierce and assigned to the assignee of the present invention. On the other hand, the prior art appears to be silent with regard to the provision of structure which includes a single shaft that is adapted to be pushed, for temporarily widening the sheet feeding gap to accommodate overly thick sheets, and rotated for selectively adjusting the gap to a predetermined width to accommodate the sheets which are of substantially the same thickness in a given stack of sheets. Accordingly:
An object of the present invention is to provide improved sheet separating and feeding apparatus;
Another object is to provide sheet separating and feeding apparatus which includes improved means for adjusting the sheet feeding gap between the sheet separating stones and feed deck; and
Another object is to provide sheet separating and feeding apparatus which includes improved means for rapidly raising the sheet separating stones to accommodate feeding thicker-than-usual sheets.